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memrchr.c revision 1.2.2.2 
      1  1.2.2.2  jym /*	$NetBSD: memrchr.c,v 1.2.2.2 2009/05/13 19:18:27 jym Exp $	*/
      2  1.2.2.2  jym 
      3  1.2.2.2  jym /*-
      4  1.2.2.2  jym  * Copyright (c) 2008 The NetBSD Foundation, Inc.
      5  1.2.2.2  jym  * All rights reserved.
      6  1.2.2.2  jym  *
      7  1.2.2.2  jym  * This code is derived from software contributed to The NetBSD Foundation
      8  1.2.2.2  jym  * by Christos Zoulas.
      9  1.2.2.2  jym  *
     10  1.2.2.2  jym  * Redistribution and use in source and binary forms, with or without
     11  1.2.2.2  jym  * modification, are permitted provided that the following conditions
     12  1.2.2.2  jym  * are met:
     13  1.2.2.2  jym  * 1. Redistributions of source code must retain the above copyright
     14  1.2.2.2  jym  *    notice, this list of conditions and the following disclaimer.
     15  1.2.2.2  jym  * 2. Redistributions in binary form must reproduce the above copyright
     16  1.2.2.2  jym  *    notice, this list of conditions and the following disclaimer in the
     17  1.2.2.2  jym  *    documentation and/or other materials provided with the distribution.
     18  1.2.2.2  jym  *
     19  1.2.2.2  jym  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     20  1.2.2.2  jym  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     21  1.2.2.2  jym  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     22  1.2.2.2  jym  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     23  1.2.2.2  jym  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     24  1.2.2.2  jym  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     25  1.2.2.2  jym  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     26  1.2.2.2  jym  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     27  1.2.2.2  jym  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     28  1.2.2.2  jym  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     29  1.2.2.2  jym  * POSSIBILITY OF SUCH DAMAGE.
     30  1.2.2.2  jym  */
     31  1.2.2.2  jym #include <sys/cdefs.h>
     32  1.2.2.2  jym #if defined(LIBC_SCCS) && !defined(lint)
     33  1.2.2.2  jym __RCSID("$NetBSD: memrchr.c,v 1.2.2.2 2009/05/13 19:18:27 jym Exp $");
     34  1.2.2.2  jym #endif /* LIBC_SCCS and not lint */
     35  1.2.2.2  jym 
     36  1.2.2.2  jym #include <assert.h>
     37  1.2.2.2  jym #include <string.h>
     38  1.2.2.2  jym 
     39  1.2.2.2  jym void *
     40  1.2.2.2  jym memrchr(const void *s, int c, size_t n)
     41  1.2.2.2  jym {
     42  1.2.2.2  jym 	_DIAGASSERT(s != NULL);
     43  1.2.2.2  jym 
     44  1.2.2.2  jym 	if (n != 0) {
     45  1.2.2.2  jym 		const unsigned char *p = (const unsigned char *)s + n;
     46  1.2.2.2  jym 		const unsigned char cmp = c;
     47  1.2.2.2  jym 
     48  1.2.2.2  jym 		do {
     49  1.2.2.2  jym 			if (*--p == cmp)
     50  1.2.2.2  jym 				return __UNCONST(p);
     51  1.2.2.2  jym 		} while (--n != 0);
     52  1.2.2.2  jym 	}
     53  1.2.2.2  jym 	return NULL;
     54  1.2.2.2  jym }
     55